A method for preparing a milk protein hydrolysate is known, for example, from U.S. Pat. No. 5,039,532 according to which a lactoserum product is hydrolyzed enzymatically, in a batchwise or semi-continuous manner, in two hydrolysis steps separated by a heat treatment step. At the end of the second hydrolysis step, the enzyme is inactivated by a final heat treatment, which promotes its self-digestion.
According to another method, described for example in U.S. Pat. No. 4,981,704, a partial hydrolysate of lactoserum proteins is prepared by enzymatic hydrolysis and, after heat treatment, the enzymes and unhydrolyzed residual proteins are separated by ultra-filtration and the hydrolysate is collected as a permeate containing the desired peptides and amino acids.
In these known methods, an excess of the enzyme is used, which must then be removed. Enzymes are very expensive and the severe heat treatments needed to inactivate the enzyme results in a deterioration of product quality in the form of impaired coloration or taste, instability of emulsions present therein, or decreased nutritional value. Thus, a new method which avoids these problems is needed.